Simplify the following expression: $\sqrt{27} - \sqrt{12}$
First, try to factor any perfect squares out of the radicals. $= \sqrt{27} - \sqrt{12}$ $= \sqrt{9 \cdot 3} - \sqrt{4 \cdot 3}$ Separate the radicals and simplify. $= \sqrt{9} \cdot \sqrt{3} - \sqrt{4} \cdot \sqrt{3}$ $= 3\sqrt{3} - 2\sqrt{3}$ Finally, simplify by combining the terms. $= ( 3 - 2 )\sqrt{3} = \sqrt{3}$